The effect of cerebral ischemia on acetylcholine (ACh) metabolism was investigated in the same gerbil model of ischemia which has been used to study other metabolic pathways in order to examine the patho-mechanism involved in ischemic tissue injury, and at the same time to provide clues for a possible single or multifactorial approach for prevention and/or therapy. Transient forebrain ischemia (15 min) induced an increase in extracellular ACh concentration, concomitant with a reduction in endogenous ACh level and increase in tissue choline content. The recirculation lead to a significant reduction of the extracellular ACh concentration during the early time of reflow, followed by a significant transient increase in the ACh release between 1 and 3 hr of reflow, with subsequent normalization. In the meantime, a rebound of the tissue ACh levels was found during the early time of reflow, followed by a gradual normalization after 2 hr of reperfusion, whereas the rapid decrease in tissue choline levels occurred after 30 min of reflow. These data represent the first report of a biphasic striatal ACh release occurring during transient ischemia and reperfusion, assessed by cerebral microdialysis in gerbils.